Tbh if the battery is ok and one has fitted a generic BMS so that it charges and the charge is good 41.5v to 42v , I would gho the whole hog and dump all parts that expect some sort of handshaking.
For less then £100 one can have a bike that uses all generic electrics and simply replace the controller and display with KT set up , then one will never need to look for any special components again.
Keep it all KISS and dump all handshaking components and convert to a generic set up, so much easier then messing about.
Handshaking adds complecations and also adds so much more to to price of components becauase they are exclusive to the bike brand.
Why pay 100's of £££'s for a specific BMS (even if it was available ) like wise a display or controller shoul done fail when one can buy something far better and readily available for cheaper .